Are gastric mucosal macrophages responsible for gastric injury in acute pancreatitis?

AIM:To investigate the protective effect of clodronatecontaining liposomes against severe acute pancreatitis(SAP)-triggered acute gastric mucosal injury(AGMI) in rats.METHODS:Clodronate- and phosphate-buffered saline(PBS)-containing liposomes were prepared by reverse-phase evaporation.The SAP rat model was established by injecting sodium taurocholate into the pancreatic subcapsular space.Sprague-Dawley rats were randomly divided into three groups:control(C),SAP plus PBS-containing liposome(P) and SAP plus clodronate-containing liposome(T).Serum tumor necrosis factor(TNF)-α levels were estimated by ELISA.Pathological changes in the gastric mucosa and pancreas were observed by hematoxylin and eosin(HE) staining.Apoptotic cells were detected by terminal deoxynucleotidyl transferase d UTP nick end labeling staining.The numbers of macrophages in the gastric mucosa were analyzed by CD68 immunohistochemical staining.RESULTS:The liposomes had a mean diameter of 150 ± 30 nm.The TNF-α levels were significantly higher in the P group than that in the C group(2 h,145.13 ± 11.50 vs 23.2 ± 2.03; 6 h,245.06 ± 12.11 vs 30.28 ± 6.07,P < 0.05),and they were significantly lower in the T group than that in the P group(2 h,93.24 ± 23.11 vs 145.13 ± 11.50; 6 h,135.18 ± 13.10 vs 245.06 ± 12.11,P < 0.05).The pathological scores of the pancreas were lower in the T group than in the P group(2 h,1.88 ± 0.83 vs 4.13 ± 0.83; 6 h,2.87 ± 0.64 vs 6.25 ± 0.88,P < 0.01).The pathological scores of the gastric mucosa were also lower in the T group than in the P group(2 h,1.12 ± 0.64 vs 2 ± 0.75; 6 h,1.58 ± 0.53 vs 3 ± 1.31,P < 0.05).In addition,increased CD68 levels were observed in the gastric mucosa of the P group compared with the C group.Clodronate-containing liposomes decreased the CD68 levels in the mucosa of the T group.The apoptotic indexes of the gastric mucosa were higher in the T group than in the P group(2 h,15.7 ± 0.92 vs 11.5 ± 1.64; 6 h,21.12 ± 1.06 vs 12.6 ± 2.44,P < 0.01).CONCLUSION:Gastric macrophages contribute to the pathogenesis of gastric injury in SAP.Clodronatecontaining liposomes have protective effects against AGMI in rats with SAP.